diff --git a/src/command-registry.coffee b/src/command-registry.coffee
index a9b953536..870093e2f 100644
--- a/src/command-registry.coffee
+++ b/src/command-registry.coffee
@@ -92,10 +92,10 @@ class CommandRegistry
         disposable.add @add(target, commandName, callback)
       return disposable
 
-    if typeof target is 'string'
-      if typeof callback isnt 'function'
-        throw new Error("Can't register a command with non-function callback.")
+    if typeof callback isnt 'function'
+      throw new Error("Can't register a command with non-function callback.")
 
+    if typeof target is 'string'
       validateSelector(target)
       @addSelectorBasedListener(target, commandName, callback)
     else